Unfortunately I can't I don't have the APK version and for some reason my computer's printscreen is not working and the quality of the photos I took don't help much so I'll say the name of the place and tell how to get into the cave, go to the river's bank at any time and bring a light source with you can be a torch or any other, if you wandered around enough there should be an option of 'enter the cave' equip your light source and go in in this cave there will be three choices choose to go down the shaft after that a minigame like the junkyard will appear and you'll only need to go to the interrogation marks on the screen first go to the one that's higher on the screen even if you don't get on top of it there should be a hole on the wall to allow you to talk with the prisoner, after that go to the one lower and talk with the succubus. If you don't have the option to enter the cave in the river's bank just wander around for awhile and it'll appear eventually. Sorry for the long response but can't send pictures (T_T)